Re: Cans of 'base' paint?
I think someone was pulling your leg, half a dozen drops of colorant isn't going to make any difference in the overall composition of the paint. As long as the paint is exterior grade and the same sheen, mix them together and paint your barn. If you do want a different color, then take them to any vendor and have colorant added. One thing you will want to do is to mix each can thoroughly with a power wand on a drill, as well as mixing the cans together. Any paint that's been sitting for more than 24 to 48 hours has a significant portion of it's pigments settled out to the bottom of the can.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!